Operator vs. material influence on clinical outcome of bonded ceramic inlays

The aim of the present study was to clinically evaluate the suitability of Definite Multibond and Definite ormocer resin composite for luting of Cergogold glass ceramic inlays in a two-center trial involving two dentists.

Thirty-nine patients received 98 Cergogold inlays with at least one inlay luted with Definite Multibond/Definite (n=45) and at least one inlay luted with Syntac/Variolink Ultra (n=53) in a split mouth design. Treatments were carried out in two private practices by two operators (Operator A: n=38; Operator B: n=60). Forty-four cavities required caries profunda treatment, 23 cavities exhibited no enamel at the cervical margin. At baseline (2 months), and after 6, 14, 27, and 51 months of clinical service, the restorations were investigated according to modified USPHS criteria.

The drop-out rate was 3% after 4 years. After 48 months of clinical service, 21 restorations in 16 patients (9 luted with Definite, 12 with Variolink; 2 placed by operator A and 19 by operator B) had to be replaced due to inlay fracture (n=11), tooth fracture (n=4), hypersensitivities (n=3), or marginal gap formation (n=3). Seventy-seven inlays were in good condition (survival rate 89.9%, median survival time 4.2 years (95% confidence interval +/-0.25; survival analysis by Kaplan-Meier algorithm). Survival rate after 4 years was 97.4% for operator A, and 75.4% for operator B (p=0.002; Log Rank/Mantel-Cox) resulting in annual failure rates of 0.6% and 6.2%, respectively. The operators did not differently judge the clinical behaviour of the luting procedures (Mann-Whitney U-test, p>0.05). Independent of the operator and the used luting system, the following criteria significantly changed over time: color match, marginal integrity, tooth integrity, inlay integrity, sensitivity, hypersensitivity, and X-ray control (p<0.05; Friedman test). Significant differences between operators over the whole period were computed for the criteria marginal integrity, tooth integrity, and inlay integrity (p<0.05, Mann-Whitney test). Differences between luting materials were only present during single recalls.

For luting of ceramic inlays, only slight differences between the two luting systems were detectable. The operator influence on clinical outcome was clearly proven.